1. Field of the Invention
The claimed invention relates generally to turbochargers designed to increase internal combustion engine performance, and more specifically to turbochargers utilizing laminar air flow to increase turbocharger efficiency and performance.
2. Description of the Prior Art
Turbochargers have typically used a turbine driven by exhaust gas from an internal combustion engine to drive a compressor for compressing air that is injected into the engine intake of the internal combustion engine in order to increase power output and efficiency.
There are several factors leading to engine power and efficiency. One key factor to creating power is the amount of fuel that can be burned which is directly related to the amount of air that can be used in the engine. The second is engine compression ratio; greater compression ratio results in greater power and efficiency. Compression ratio is limited due to knock in spark ignited engines, which will damage an engine and reduce power. Of importance to this invention, two of the many variables resulting in knock are the amount of air mass in the combustion chamber and the temperature of the air. Low air mass and low temperatures result in lower chance of engine knock. Therefore, highest engine power is achieved by high mass airflow of cool air and the highest possible compression ratio. This increase in power output and efficiency is accomplished by increasing the mass flow rate of air injected in the engine intake of the internal combustion engine.
However, compression of the air that is injected into the engine intake results in making the flow of the air turbulent and increases the temperature of the air to be injected. This creation of turbulence and increased temperature are undesirable by products of providing a high mass flow rate of air to the engine intake. In order to counter these effects, the prior art typically employs a diffuser to reduce air turbulence and intercoolers to control air temperatures. In diesel engines, the upper temperature limit of intake air charge is dictated by emissions, as higher temperature air mass negatively impacts an engine""s emission output.
The turbine, which typically consists of a housing and a bladed rotary wheel vane attached to a shaft, drives the compressor. The bladed rotary wheel vane usually employs complicated vane geometry to transfer the linear energy of the exhaust gases entering the turbine into rotational energy that drives the compressor. These types of turbines are often expensive to manufacture and are relatively inefficient. The size of the turbine is typically governed by the power characteristics of the internal combustion engine on which it will be used.
The compressor typically consists of a housing and a bladed impeller. Air is inlet into the compressor and compressed between the impeller blades and the housing which increases the mass of air within a given volume. This compressed air is then injected into the engine intake. The size of the compressor is typically governed by the power characteristics of the internal combustion engine on which it will be used.
The air intake requirements of the internal combustion engine varies during engine operation due to fluctuating demand. This requires the turbocharger to be capable of varying the pressure and volume of air input relative to engine requirements. Current technology utilizes bypass mechanisms that vent engine exhaust gases around the turbine in order to diminish the velocity of the system which reduces the output of the compressor.
There are several turbochargers disclosed in the prior art that operate as here described. Some examples are U.S. Pat. Nos. 5,406,796, 4,367,626, 4,124,979, and 3,975,911. U.S. Pat. No. 5,406,796, issued to Hiereth, comprises a compressor driven by a turbine that is on the same shaft which is driven by exhaust gas from an internal combustion engine. U.S. Pat. No. 3,975,911, issued to Borisovich, is comprised of a compressor driven by a turbine that is on the same shaft which is driven by exhaust gas from an internal combustion engine. In addition, Borisovich also discloses the use of a diffuser to reduce turbulence in the air that is being injected. U.S. Pat. No. 4,124,979, issued to Tholen, discloses a turbocharger that uses an intercooler to control the temperature of the air that is being injected into the internal combustion engine.
Turbochargers use energy from four or two stroke engines exhaust to pump intake air into said engine. High pressure exhaust gases rotate the driver of the turbine which in turn rotates the compressor of the system that is on the same shaft. The compressor then pumps air into the intake portion of the engine. Current turbocharger compressors and drivers utilize complicated vane geometry to impart air movement. These are relatively inefficient which results in insufficient use of exhaust gases and heating of output air from the turbocharger. The geometry of these components is difficult and expensive to manufacture. Accordingly, it would be desirable to have a turbocharger that makes more efficient use out of the energy provided by the exhaust gases without increasing the turbulence and temperature that is associated with increasing the mass flow rate of air entering the internal combustion engine.
Accordingly, it is the object of the claimed invention to provide a turbocharger that can efficiently increase the power output of the internal combustion engine by increasing the mass flow rate of air that enters a engine intake of the internal combustion engine with a reduced amount of turbulence and temperature change imparted upon the air entering the engine intake.
Another object of the claimed invention is to provide a turbocharger that reduces exhaust manifold back pressure. The turbocharger of the claimed invention reduces exhaust manifold back pressure by providing a turbine that is designed to be less restrictive to the exhaust gases entering the turbine.
Still another object of the claimed invention is to reduce the manufacturing costs associated with the production of a highly efficient turbocharger. Due to the less complex geometry of the claimed invention, the overall cost of manufacturing a turbocharger capable of improving the power output of an internal combustion engine is reduced significantly.
To achieve the foregoing and other objectives, and in accordance with the purposes my invention, a bladeless turbocharger comprising both a blower and a turbine of similar designs known herein as a bladeless blower and a bladeless turbine is provided. The bladeless turbocharger utilizes engine exhaust gases from an internal combustion engine entering the bladeless turbine to drive the bladeless blower that produces a charge air to an internal combustion engine for the purpose of increasing engine power. Both the bladeless blower and the bladeless turbine are comprised of flat rigid spaced disks contained in an annular shaped volute that utilizes laminar viscous boundary layer drag to achieve more efficient results.
It is well known that fluids have a resistance to flow adjacent to a stationary surface known as the boundary layer effect. This boundary layer is the region of fluid adjacent to the surface in which viscous forces promote laminar fluid flow. The boundary layer thickness is defined as the distance from the surface to a point within the fluid stream where the velocity of the fluid is within one percent of the free stream velocity. The mass flow rate of fluid within the boundary layer is higher than that within the free stream due to the higher efficiency of laminar flow. Accordingly, the mass flow rate of fluid adjacent to a solid moving surface is greater than the mass flow rate of fluid that would pass through the same region in the absence of the boundary layer effect. My invention utilizes the laminar flow of fluid present within the boundary layer effect to accomplish the aforementioned intention of a system producing a cool air charge for an internal combustion engine powered by the engine""s exhaust gases.
Current turbocharger technology normally requires the use of a diffuser to diminish the turbulence imparted to the air charge before it is introduced into the intake portion of the engine. Highly turbulent air negatively impacts efficient air flow. In my invention, the viscosity of air acting against the moving blower disks produces circular air flow between blower disks. The resulting annular air speed and centrifugal forces create pressure and air flow. The non turbulent nature of air flow between the blower disks results in increasing the effective mass of air delivered for combustion while not appreciably increasing the ambient air temperature.
The exhaust gases exiting the internal combustion engine enter the system at an impinging angle to a collection of contained disks on the turbine side of the system through specially designed ports. This reduces engine exhaust manifold back pressure due to the engine exhaust entering the bladeless turbine not being restricted by a rotary wheel vane. This method is of higher efficiency and therefore produces less back pressure to achieve the same turbocharger shaft power. This causes the collection of disks to rotate at a high velocity consistent with the speed of the exhaust gases. The engine exhaust gases, by reason of their resistance to flow over a body of different speed, upon entering through the inlets and coming in contact with the disks, are subject to viscous laminar flow acting tangentially in the direction of rotation. Exhaust gas pressure forces exhaust air towards the center of the disk. The disks will be set in motion rotationally with the engine exhaust gases moving in a spiral path at a continuously diminishing velocity until they reach the center of the disk where they are discharged.
This rotation in turn causes the disk of the blower side of the system to rotate at the same rotational velocity since the disks are affixed to the same shaft. The same principles apply with regard to the factor of viscous laminar flow. Ambient temperature inlet air is accelerated to a velocity consistent with the perimeter velocity of the rotating disks into the outlet passage of the device and subsequently into the intake portion of the internal combustion engine. The combined effect of these tangential and centrifugal forces is to propel the inlet air with an increasing velocity in a spiral path until it reaches a suitable peripheral outlet from which it is ejected. If the disks are allowed to turn freely owing to an adequate bearing system, the rim of the disk will attain a speed closely approximating that of the exhaust gases and the spiral path of the gases will be comparatively long and consist of almost circular annular turns.
Since this spiral movement of air is free and undisturbed and essentially dependent on the properties of the air permitting it to its natural stream lines and to change its velocity and direction by minimal increments of degrees it does not cause turbulence in the air. Since the air is compressed in a manner utilizing laminar flow there is an increase in air density delivered to the intake portion of the internal combustion engine over current technology. This feature is essential to the successful operation of this invention. Of course, air is heated when compressed as per the ideal gas law. It is the heating due to inefficiencies that is minimized.
Each engine application will require a reconfiguration of the diameter and/or the number of disks in the assemblies to accommodate the flow of air required for each specific engine size. Currently, there are specific engine mapping processes that describe optimum engine requirements (air charge volume and pressure) at specific engine performance characteristics. These requirements will vary according to each engine size and are available in publications available in the public domain. My invention has demonstrated that the configuration utilized reveals adequate operation of these principles and other disk diameters and/or change in number of disks may improve the invention""s performance for differing applications.
Internal combustion engine""s air intake requirements vary during engine operations due to fluctuating demand. This fact requires that the turbocharger be able to vary the pressure and volume of output relative to engine requirements. Current technology utilizes bypass mechanisms that vents engine exhaust gases around the turbine in order to diminish the velocity of the system which reduces the output of the compressor. Since the laminar air flow characteristics of the claimed invention do not create significant increased temperature of the air, the output control of the system is accomplished by restricting inlet air to the blower rather than diminishing the system""s rotational velocity. This characteristic allows for the system to run at maximum velocity at all times and produces an immediate response to air demand for combustion during the varying operating conditions of the engine.
In order to optimize performance at low engine speeds, the turbine volute may utilize a variable nozzle. By decreasing the cross sectional area of the turbine nozzle the velocity of exhaust gas entering the turbine increases. This will reduce turbocharger lag, an undesirable characteristic of all turbochargers.
To achieve the foregoing and other objectives, and in accordance with the purposes of the present invention, a bladeless turbocharger is provided. The bladeless turbocharger includes a bearing assembly with a drive shaft having a first end portion and a second end portion passing through and rotationally engaged with the bearing assembly. A bladeless turbine is mounted to the first end portion of the drive shaft, and a bladeless blower is mounted to the second end portion of the drive shaft.
The bladeless turbine comprises a turbine volute, an inner turbine wall adjacent the turbine volute, and an outer turbine wall adjacent the turbine volute and opposite the inner turbine wall. A plurality of parallel flat turbine disks are contained in the turbine volute spaced at a critical distance apart having open circular centers with a plurality of spoke like projections fixedly mounting the turbine disk centers to the first end portion of the drive shaft, the critical distance permitting only boundary layer drag effect activity of exhaust gas from the internal combustion engine within the critical distance. The critical distance is dependent upon several factors such as the type of internal combustion engine, the surface finish of the disks, and the ambient air temperature and pressure. The preferred embodiment of the invention has a critical distance spacing from about 0.006xe2x80x3 to about 0.012xe2x80x3. In other embodiments of the claimed invention, the critical distance can be as much as 0.050xe2x80x3 depending upon the turbocharger application.
At least one turbine inlet is provided within the wall of the turbine volute in tangential relation to the periphery of the turbine disks capable of allowing the exhaust gas to enter the turbine tangentially to the periphery of the turbine disks, the exhaust gas pushed through the turbine inlet by the exhaust stroke of the internal combustion engine into the critical distances between the turbine disks rotating the turbine disks and the drive shaft by energy transferred from the exhaust gas through boundary layer drag effect of the exhaust gas against the turbine disks.
A turbine outlet is provided within the outer turbine wall axially adjacent the open circular centers of the turbine disks capable of allowing the exhaust gas to exit the bladeless turbine through the open circular center of the turbine disks.
The bladeless blower driven by the drive shaft, comprises a blower volute, an inner blower wall adjacent the blower volute, an outer blower wall adjacent the blower volute and opposite the inner blower wall. A plurality of parallel flat blower disks contained in the blower volute spaced at the critical distance apart having open circular centers with a plurality of spoke like projections fixedly mounting the blower disk centers to the second end portion of the rotating drive shaft, the critical distance permitting only boundary layer drag effect activity of air within the critical distance.
A blower inlet is provided within the outer blower wall axially adjacent the open circular centers of the blower disks, the blower inlet capable of allowing the air to enter the blower through the open circular centers of the blower disks into the critical distances between the blower disks, the air being drawn in through the blower inlet due to the pressure difference created by the blower disks rotating within the blower volute whereby the rotational energy of the blower disks is transferred to the air by boundary layer drag effect activity of the air against the rotating blower disks thereby increasing the mass per unit volume of air.
A blower outlet is provided that is configured within the wall of the blower volute determined by the Fibonacci formula and in tangential relation to the periphery of the blower disks, the blower outlet capable of allowing the air of increased mass per unit volume to exit the bladeless blower tangentially to the periphery of the blower disks into a engine intake of the internal combustion engine.
Other features of the claimed invention include labyrinth seals of concentric interrelated ridges between the inner and outer turbine disks and the inner and outer turbine walls. Similarly, the blower may also have labyrinth seals between the inner and outer blower disks and the inner and outer blower walls.
Further, the turbine may also have at least one variable nozzle contained in the turbine inlet so that the cross sectional area of the inlet can be increased or decreased depending upon the operating conditions of the turbocharger. Similarly, the blower may have at least one variable nozzle so that the cross sectional area of the blower inlet may be increased or decreased.